Angioplasty procedures have gained wide acceptance in recent years as efficient and effective methods for treating many types of vascular disease. In particular, angioplasty is widely used for opening stenosis or occlusions in the coronary arteries, although it is also used for the treatment of stenosis in other parts of the vascular system.
The most widely used form of angioplasty makes use of a dilation catheter which has an inflatable balloon at its distal end. Inflation of the balloon at the site of the occlusion causes a widening of the vessel or artery to reestablish an acceptable blood flow through the vessel or artery.
It often is desirable to determine the severity of the occlusion in order to properly choose a dilation catheter or to make a determination as to whether treatment is required. Various techniques have been used to determine the severity of the occlusion. One way of determining the severity of the occlusion is to measure pressure both proximal to and distal of the occlusion.
Specifically, referring to FIG. 1 (which does not illustrate a prior art device, but which instead illustrates one disclosed embodiment), two occlusions 11, 12 are shown in an arterial wall 13. In determining the severity of the occlusion 11, knowledge of the ratio of the pressures P2:P1 is important. A ratio of P2:P1 of less than 0.75 is indicative of an occlusion requiring treatment and a ratio of P2:P1 of greater than 0.75 is indicative of an occlusion not requiring treatment. Similarly, with reference to the occlusion shown at 12 in FIG. 1, if the ratio P3:P2 is less than 0.75, it would be an indication that the occlusion 12 would require treatment. If the ratio P3:P2 is greater than 0.75, it would be an indication that the occlusion 12 does not require treatment.
Devices that are used for this purpose include catheter-like members with some type of pressure-sensing device incorporated therein. One known device measures the pressure as a function of the deflection of a diaphragm located at the proximal end of the catheter. One problem associated with currently available pressure-sensing devices is that they are unable to measure pressure at points both proximal and distal to the occlusion without moving the device. When the device or catheter is moved, it can often cause physical changes to the occlusion thereby affecting the second pressure measurement. Further, unnecessary movement of the catheter can dislodge a portion of the plaque that forms the occlusion. Further, because it is often difficult to insert catheters in coronary arteries and other vessels, physicians are often reluctant to move a catheter in a proximal direction once the catheter is in position. Hence, once a physician inserts a catheter past the point of occlusion, the physician is often reluctant to move the catheter to a point proximal to the occlusion to take a pressure measurement if a catheter must be moved back to a location distal to the occlusion at a later time in the procedure.
Accordingly, there is a need for an improved intravascular pressure-sensing device which can monitor and measure pressure at multiple points along a vessel or artery without moving the device. Still further, there is a need for an intravascular pressure-sensing device which can monitor and measure pressure at multiple points along a vessel or artery simultaneously.
It would be desirable to make use of both multi-point intravascular pressure sensing devices and methods in order to provide a physician with sufficient diagnostic information to make a determination as to whether the occlusion should be treated. The ideal multiple point pressure measurement device would be accurate, low profile, flexible and have a fast response time. Both the cost and ease of use of the complete system needs to be considered as well to produce a commercially successful product. Presently available devices are not capable of simultaneously meeting these various requirements.